VDI Reports 612, Electronics in Automotive Construction describes a so-called CAN system. This system introduces the use of networked subsystems instead of the use of single, separate control units. The CAN system has separate control units that assume various functions, such as controlling the fuel injection process, automatic transmission control, as well as other tasks. In this type of system, all of the control units are connected to each other, as well as to all of the sensors and actuators. Difficulties arise in such a system when the various control units send conflicting control signals to the performance-regulating servo unit. Thus, one control unit may call for a decrease in the power output, while another control unit for an increase in the power output.
German Published Patent Application 33 31 297 (U.S. Pat. No. 4,583,611) describes a device for preventing the drive wheels of a motor vehicle from rotating by setting a power-regulating positioning unit in a direction of lesser power output. Such a device is commonly referred to as a drive slip control (ASR). Typically in such systems, however, the brakes are also controlled.
German Published Patent Application 28 48 624 (U.S. Pat. No. 4,266,447) describes a method for controlling automatic transmissions. According to this method, when the gear unit is actuated, a power-regulating positioning unit is controlled in a particular manner.
In systems which employ an automatic transmission control in addition to a drive slip control, it is possible for the drive slip control and the automatic transmission control to influence the quantity of fuel to be injected at the same time or at overlapping times. Any interventions, i.e., adjustments, in the fuel quantity by the automatic transmission control must not be hindered by the interventions of another control unit, otherwise, the gear of the transmission will not be able to be engaged. Similarly, intervention by the drive slip control must not be hindered by other power-regulating interventions.
One of the objects of the present invention is to provide a system to determine which of a plurality of control units acting simultaneously on a power-regulating positioning unit will actually control the positioning unit.